Magnesium-manganese-zinc alloys



Patented Nov. 1, 1'932 UNITED STATES PATENT oFFicE JOHN A. GANN, 0F MIDLAND, MICHIGAN, ASSIGNOR TO THE DOW CHEMICAL COMPANY, 01'

MIDLAND, MICHIGAN,

A CORPORATION OF MICHIGAN MAGNESIUH-MANGANESE-ZI NG ALLOYS No Drawing.

The present invention relates to'ternary magnesium alloys in which magnesium is the predominant metal, and specifically to magnesium-manganese-zinc alloys.

Magnesium is the lightest of the engineering metals. This property inconnection with good tensile strength makes it a highly desirable metal where reduction in weight is a prime consideration as in air and land vehicles. Accordingly, numerous efforts have been made to produce suitable alloys for such uses. The addition of zinc to magnesium in order to make a binary light metal alloy has been heretofore described in U, S. Patent No. 982,022 to Riibel dated Jan. 17 1911,

v the stated proportions of the zinc being not less than 1 per cent nor more than 6 per cent, and in a more recent U. S. Patent No. 1,377,374 to William R. Veazey dated May 10, 1921, a binary alloy is disclosed consisting of magnesium to which manganese has been added. However, I have discovered by I carrying'out many extensive investigations and numerous carefully conducted tests both of a scientific character and under conditions of practical use that a ternary alloy containing all three of the elements magnesium, manganese, and zinc will largely overcome or mitigate the drawbacks of each of the above noted binary alloys, and at the same time produce an alloy having substantially all of their good properties.

Accordingly, among the objects of the present invention is the production of ternary alloys containing magnesium, manganese, and zinc, such alloys having high corrosion resistance and superior mechanical properties. Other objects and advantages will appear as the description proceeds.

The invention, then, consists of the new product consisting of a ternary alloy of the metals magnesium manganese, and zinc as hereinafter fully described and particularly set forthin the claims. The following description, it will be understood, thus sets forth but several of various ways in which the in- Application filed November 20, 1930. Serial no. 497,075.

alloy. The following table gives the prop- I 'erties of these alloys in the as cast state.

Properties of sand cast magnesium alloys Tensile strength #/sq. in 26000 18000 26000 Yield point #/sq. in 5000 -3500 5000 Per cent e1ongation 12 8 11 Brinell hardness 37 34 37 mpact-ft. lbs 11 10 12 Referring to the table, it is noted that the ternary magnesium-manganese-zinc alloy is superior in every way to the corresponding binary magnesium-manganese alloy. Its mechanical properties likewise very closely approximate those of the corresponding bmary magnesium-zinc alloy. It is thus to be seen that the addition of zinc to a binary magneslum-manganese alloy makes a verymarked improvement in its mechanical properties, and accordingly, the new ternary alloy can be considered as an improvement over the binary magnesium-manganese alloy. The corrosion resistance of the ternary magnesium-' manganese-zinc alloy further is far superior to that of the binary magnesium-zinc alloy and very closely approaches that of the bin'ary magnesium-manganese allow which at the present timeexhibits the best corrosion resistance of any magnesium alloy being produced. To summarize the above, the new ternary magnesium-manganese-zinc alloys have a corrosion resistance closely approaching that of the highly corrosion resistant binary magnesium-manganese alloys, and at the same time have mechanical properties substantially equivalent to binary magnesium-,

zinc alloys which are among the strongest of the binary magnesium alloys. These new ternary alloysaccordingly are exceptionally well suited to usages where both strength and corrosion resistance are essential. I The improved ternary magnesium-manganese-zinc alloys can be formed from their components, for instance by melting a quantity of magnesium and adding thereto the metals manganese and zinc or by adding to the molten magnesium a manganese-zinc alloy. Another satisfactory method of adding manganese to the'metal consists, as described in the above noted U. S. Patent No. 1,37 7 ,37 4 to W. R.Veazey, in contacting molten magnesium or magnesium alloy with a reducible man ese compound which reacts with such meta to liberate manganese metal in condition for direct alloying therewith. While the manganese may be present in the ternary alloys in amounts of from 0.1 to 3.0 per cent or more, I normally prefer to keep the manganese content within the range of 0.5 to-1.5 per cent. Zinc, on the other hand, may be present in amount from 0.5 to 16.0 per cent, although I normally prefer to keep within the ran .of 1.0 to 6.0 per cent. From m extensive work with this new alloy I have ound that where such ternary alloy contains approximately 95.6 per cent magnesium, 1.4 per cent 'manganese, and 3.0 per cent zinc, it is suitable -for manyuses, particularly where corrosion resistance, as well as strength is uired. bther modes of applying the principle of my invention may employed instead of those explained, change being made as regards the com 'tion herein disclosed, provided the ingredients stated by any of the followinglclaims or the equivalent of such stated 'ents be emplo ed.

therefore part1c arly point out and distinctly claim as my invention 1. As a new product, an alloy containing manganese is present in amount from 0.1.to 3.0 per cent, zinc in amount from 1.5 to 16.0 per cent, the balance being substantially magnesium.

2. As a new product, an alloy consisting of magnesium in amount in excess of per cent and up to 99.4 per cent, manganese between 0.1 and 3.0 per cent, together with zinc in amount from 0.5 to 16.0 per cent.

3. As a new product, a ternary magnesiummanganese-zinc alloy wherein the magnesium is present in amount from 82.5 to 99 per cent, manganese from 0.5 to 1.5 er cent, and zinc from 0.5 to 16.0 per cent, t e zinc content of the alloy exceeding the manganese.

4. As a new'product,'a ternary alloy of commercially pure magnesium, manganese, and zinc, wherein the magnesium is present in amount from approximately 88 to 99.5 per f cent, manganese in amount from 0.1 to 2.0 per magnesium, manganese, and zinc, wherein the cent, and zinc in amount from 0.5 to 10.0 per cent.

5. As a new-product, an alloy consisting of magnesium in amount from approximately 92;to 98.5 per cent, manganese between 70 0.5 and 1.5 percent, together with zinc in amount of 1.0 to 6.0 per cent.

6. As a new product, an alloy consisting of approximately 95.6 per cent magnesium, 1.4 per cent manganese, and 3.0 per cent zinc.

Signed by me this 13th day of November,

JOHN A. GANN. 

